1. Field of the Invention
The present invention relates to a humidifier, and more particularly to a humidifier which has an ultrasonic vibrator together with a heater and can prevent the ultrasonic vibrator from being damaged due to a heat energy generated by the heater.
2. Description of the Prior Art
A humidifier is an apparatus that converts water into a mist in order to control a humidity of a space, wherein, as the means for converting the water into a mist, an ultrasonic vibrator is used or a heater is adapted additionally to the ultrasonic vibrator. The reason for adapting the heater is not only to sterilize the water, but also to produce a lot of vapor.
In using a humidifier, conditions during usage may influence the durability of the ultrasonic vibrator and the heater. In order to prevent the heater from being damaged, considering the fact that when a heating member is not immersed in water, the heater may be damaged by the overheating, the U.S. Pat. No. 5,343,551 discloses an art that indicates a lack of water by an alarm signal and thereby, a user can refill the water.
On the other hand, the ultrasonic vibrator has a vibrating member whose surface is coated by a coating material. If the temperature of the ultrasonic vibrator is kept over a limit temperature, then damage such as the ultrasonic vibrator being transformed because of thermal saturation and the coating material being detached from the vibrating member may gradually occur. Therefore, when the heater and the ultrasonic vibrator are simultaneously operated, the possibility that the ultrasonic vibrator is thermally damaged is high.
In FIG. 2, the structure of a conventional humidifier having a heater and an ultrasonic vibrator is illustrated. As known from the structure, while a heater 140 is being operated, a temperature of the water in a heating chamber 120 increases and thereby, a temperature of the water in a humidifying chamber 130 also increases. Thus, a temperature of the ultrasonic vibrator 150 in the humidifying chamber 130 also ascends. If the water temperature of the humidifying chamber 130 is kept over the limit temperature for a predetermined time, the ultrasonic vibrator 150 is thermally damaged so that a life of thereof is shortened. Accordingly, to lengthen the life of the ultrasonic vibrator 150 even though the heater 140 is being operated, it is necessary to control the water temperature of the humidifying chamber 130 so that it does not ascend over the limit temperature.